1. Field of the Invention
The present invention relates to a dielectric ceramic. In addition, the present invention relates to a laminated ceramic capacitor configured with the use of the dielectric ceramic.
2. Description of the Related Art
A laminated ceramic capacitor, one typical ceramic electronic component, has, for example, a laminated body including a plurality of stacked dielectric layers and a plurality of internal electrodes formed along interfaces between the dielectric layers; and external electrodes formed on the outer surface of the laminated body and electrically connected to the internal electrodes.
In the dielectric ceramic used for constituting the dielectric layers, BaTiO3 based compounds have been used as a main constituent of the dielectric ceramic in order to realize high dielectric constants. In particular, the use of (Ba, Ca)TiO3, a barium titanate with some of Ba substituted with Ca, can achieve high reliability and favorable temperature characteristics of capacitance in some cases.
Extremely severe demands have been made on laminated ceramic capacitors in recent years for a reduction in size and an increase in capacitance. For example, the dielectric layers have been required to have a thickness reduced to on the order of 1 μm. As a result, the intensity of the electric field applied to the dielectric layers has been increasing, thereby leading to an increasingly severe design constraint for ensuring reliability.
As a means for solving the problem described above, for example, Japanese Patent Application Laid-Open No. 2003-165768 proposes the addition of various elements to a dielectric ceramic in predetermined amounts. Specifically, Japanese Patent Application Laid-Open No. 2003-165768 proposes a dielectric ceramic represented by the general formula: (Ba, Cax)mTiO3+α1BaO+α2CaO+βV2O5, in which α1 and α2, respectively, include cases of α1=0 and α1=0, with m≧0.990, 0.0001≦β0.025, 0.02≦x≦0.15 in the relationship of 1.005<m+α1+α2<1.035, and the content of a sintering aid present is 0.2 to 5.0 parts by weight with respect to 100 parts by weight of the compound represented by the general formula.